Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 19: Poster: New Methods, Thin Polymer Films, Monolayers

CPP 19.27: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT1

Structure and Superstructure within Lipopolymeric Monolayers — •Heiko Ahrens¹, Thomas Rosleff Baekmark², Rudolf Merkel², Karlheinz Graf¹, Roberto Raiteri³, and Christiane A. Helm¹ — ¹Universität Greifswald, Angewandte Physik, D-17487 Greifswald — ²TU München, Physik Department E22, D-85748 Garching — ³Universität Genua, Department of Biophysical and Electronic Engineering, I-16415 Genova

For the first time, the formation and growth of a molecular superstructure within a lipopolymeric monolayer on the water surface is directly observed by small-angle GID-diffraction. Nanoscopic stripes of weakly ordered alkyl chains (6 nm wide) and solubilized polymer alternate, due to an equilibrium between strong short-ranged attraction and weak long-ranged polymeric repulsion. This structure can be reversibly induced by adjusting the temperature and molecular area. At the onset of the superstructure formation, the smallest stripe periodicity is measured. Then the periodicity relaxes (up to 17 nm), even if the monolayer is further compressed. This threshold behavior is attributed to a very high local pressure necessary for stripe alignment. On solid substrates, the superstructure periodicity is decreased down to 12 nm due to dehydration of the polymer moieties.